Pillar Procedure for Snoring and Sleep Apnea

About the Pillar Procedure

An estimated 70 million Americans suffer from sleep disorders such as snoring and sleep apnea1,2 that keep them and their bed partners from getting a good night’s sleep.3 Many have tried various snoring treatments and are often left frustrated.

Unlike other surgical snoring and sleep apnea treatments, the Pillar® Procedure is a simple technique you can perform in a single short office visit or in combination with other procedures. This minimally invasive treatment for snoring and sleep apnea is directed at the soft palate. Patients typically resume normal diet and activities the same day.

During the Pillar Procedure, three tiny polyester implants are placed into the soft palate. Over time, the implants – together with the body's natural fibrotic response – add structural support to and stiffen the soft palate. This reduces the tissue vibration that can cause snoring, and the palatal tissue collapse that can obstruct the upper airway and cause sleep apnea.

More than 45,000 people worldwide have been treated with the minimally invasive Pillar Procedure.

Causes of Snoring and Obstructive Sleep Apnea

The vibration or collapse of the soft palate is a significant contributor to snoring and obstructive sleep apnea. When tissue in the upper airway flutters or vibrates, it can cause snoring; obstructive sleep apnea occurs when tissue collapses and/or blocks the upper airway. Studies suggest that the soft palate is involved in more than 80% of snoring and obstructive sleep apnea patients.4,5

As muscles in the upper airway relax during sleep, unsupported or excess tissue in the back of the mouth and throat can collapse, thereby reducing the cross-sectional area of the airway. For a constant volume of inspired air, the air speed through the collapsed region must increase. Whenever there is an increase in air velocity, there is also a corresponding drop in pressure. This lower pressure leads to the creation of a lifting force similar to that of an airplane wing.

In the airway, this creates an imbalance of forces. The palate vibrates as the aerodynamic forces overwhelm the structural integrity of the palate, resulting in snoring sounds. When the negative pressure in the airway reaches a critical point, the combination of collapsible tissues and loss of muscle tone causes airway collapse or obstruction, resulting in obstructive sleep apnea.

References

1

Brain Facts, A Primer on the Brain and Nervous System. Society for Neuroscience, 2008.

This minimally invasive snoring and sleep apnea treatment takes approximately 20 minutes. You can use local anesthetic (typically, lidocaine injections) to perform the Pillar® Procedure in the office. During the procedure, you place three tiny implants at the junction of the hard and soft palate.

For maximum effectiveness, the implants are closely placed. One is placed at the midline and the other two are placed no more than 2 mm lateral of the midline implant.

The result is a contiguous structure approximately 10 mm by 18 mm that serves as an extension of the hard palate and reduces the palate’s natural tendency to flutter and/or obstruct the airway during sleep.

Placement Diagram for the Pillar Procedure Implants

Fibrotic Response to Pillar Procedure Implants

Clinical studies of the Pillar Procedure have shown that:

Patients experienced a significant decrease in snoring intensity.1,2

Bed partner satisfaction with the reduction in snoring after the Pillar Procedure has been documented at 80% or higher.1,2

Approximately 80% of patients demonstrated a reduction in their apnea hypopnea index (AHI), and results were sustained at one year after the Pillar Procedure.3

Patients experienced less daytime sleepiness and significant improvements in lifestyle after the Pillar Procedure.4

Pillar Procedure Implant Material

The current implant for the Pillar Procedure snoring treatment was selected after investigation and study of a wide variety of biocompatible materials and implant designs. The implant consists of multiple polyester fibers woven together into precise specifications. The implant deisgn requires that two ultrasonic welds melt the fibers together, creating a depression at the surface of each end to prevent unraveling.

A schematic of the implant and a photomicrograph of a section of the implant obtained by scanning electron microscopy (SEM) is shown below. The implant length is 18 mm and the diameter is approximately 2 mm.

Testing was also conducted to evaluate tissue response to the implants, which are designed to take advantage of the body's natural response to a foreign object by stimulating tissue ingrowth into each implant, forming a fibrous capsule around each implant, and generating fibrous cross-linking between the implants. This fibrotic response causes the tissue around the implants to become stiffer than the original tissue, effectively reducing both the flutter that can cause snoring and the ability of the soft palate to obstruct the upper airway. Histological results confirmed that the implants should be placed as close as possible without touching to achieve maximum stiffening. An implant should be no more than 2 mm away from an adjacent implant in order to achieve the fibrotic responses that contribute to lateral stiffening, effectively making a bridge of stiffer tissue between the implants.

Real-time imaging of the soft palate during a forced snore. Three of the successive frames from this study are shown during the act of simulated snoring. Each frame is separated in time by 1.2 seconds.

To understand the normal function of the soft palate, dynamic MRI studies were conducted. These studies illustrated the palate movements associated with swallowing and phonation, as well as simulated snoring. As shown in the following sequence, the palate is a highly mobile airway structure.

Palatal motion during the simulation of a snoring sound is characterized by extreme bending of the soft palate. Relative to the hard palate, the soft palate undergoes an approximate 120 degree central bend upwards and towards the hard palate. As a result, the soft palate appears to elevate and fold on itself as the bending occurs. This bending is initiated in proximity of the junction of the hard and soft palate. The palate is transformed from a relatively straight, hanging appendage to an exaggerated hook-like appendage during the course of the dynamic scans. These studies highlight the importance of a flexible design that provides support to address the dramatic movement that can take place high in the palate.

Pillar Procedure

Aerodynamic Airflow With The Pillar Procedure

A sophisticated computational model was utilized to evaluate the effect of an implant on airway flow and is illustrated below. Although the model is somewhat simplified, all of the major features of the human anatomy are represented.

The model consists of four walls that form a channel, replicating the human upper airway. The channel is attached to a vacuum system that draws air into the model, simulating inhalation by the lungs. A partition is placed between the upper and lower walls of the channel, replicating the hard palate and dividing the incoming airflow between "nose" and "mouth" inlets. The vertical position of both the upper and lower walls is adjustable, allowing the simulation of varying levels of airway obstruction. The soft palate, which is attached to the hard palate and channel side walls by way of a clamp, consists of a layer of flexible silicone. The angle of the soft palate relative to the incoming airflow can be varied to simulate the range of soft palate orientations that may occur with different sleep positions. When the vacuum system is activated, air is drawn into the model through the "nose" and "mouth" inlets. The walls of the channel are clear so that the motion of the soft palate during a simulated snore can be visualized. At a critical air velocity, the silicone soft palate oscillates much like that of a human soft palate during snoring.

Experiments were performed to investigate soft palate support and stiffening strategies using various iterations of a wind tunnel model. Tape was used to represent a stiffening effect without increasing the mass to the point of unrealistically dominating the structure. The experiments showed that stiffening the soft palate in a "front-to-back" fashion significantly increased the air velocity needed to initiate palatal oscillation and reduced the magnitude of the movement.

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Pillar Procedure Computational Modeling

A computational model of the soft palate was created to analyze the stiffening effect of the implants. This model was used to study the influence of implant design, placement, and size on soft palate stiffness. The goal of the analysis was to assess implant stiffening effect, given the assumptions and limitations of a model of the soft palate. The model generated the following key observation:

Pharyngeal closing pressure is a well established physiological outcome measurement in which a more negative value implies a less collapsible airway (i.e., less pressure is required to collapse the pharynx in an apneic patient).1 A finite element analysis (FEA) model of the upper airway developed at The Harvard Medical School was used to examine the effect of palatal implants on pharyngeal closing pressure.2 The results of the analysis are summarized below:

Closing Pressure (cm H2O)

Tissue Condition

Normal Tissue

Scar Tissue Only

With An Implant

Paralyzed

-6.5

-8.3

-9.0

Anesthetized

-8.5

-11.5

-13.0

Asleep

-11.5

-14.5

-17.0

The FEA demonstrates that under three diverse conditions, relative stiffening of soft palate tissue increases the pressure necessary for closure to occur. The FEA demonstrates that the addition of the palatal implants is shown to be more effective than scar tissue alone.

The magnitude of effect is similar to what has been reported in literature suggesting that the observed findings are clinically significant.2 Changes in palatal stiffness using implants have important effects on pharyngeal biomechanics. The order of magnitude of the effect is in the range that would certainly be clinically significant.